Post office Protocol very well knows as POP, in computing we can describe POP as an application-layerInternet standard protocol. POP is used to retrieve e-mail from a mail server by an email client. POP in simple language can also be known as application layer protocol in the OSI model which helps end-user to fetch and receive the email, in short, it acts as a primary protocol behind email communication.
How does Post Office Protocol work?
With the help of TCP/IP PoP stack for network connection and work with SMTP which is Simple Mail Transfer Protocol which establishes and end to end email communication, here simply POP pull messages whereas SMTP pushes them to the server. Currently POP is in its third version which is commonly known as POP3 which is now used on email client/server communication architecture. Both IMAP and POP deal with the receiving of an e-mail, therefore, they should not be confused with the Simple Mail Transfer Protocol (SMTP), which is a protocol for transferring e-mail throughout the Internet.
The conventional port number for POP3 is 110.